1. Field of the Invention
The present invention relates to an information recording apparatus for recording data on a write-once information recording medium that can be written on only once, such as a CD-R and a DVD+R, and a rewritable information recording medium, such as a CD-RW and a DVD+RW, an information recording method thereof, a program for a computer to carry out the information recording method, a computer-readable recording medium for storing the program, and an information recording system wherein the information recording apparatus records data on the write-once information recording medium and the rewritable information recording medium based on instructions from a host computer.
2. Description of the Related Art
As for the rewritable information recording media, on which data can be rewritten a large number of times, CD-RW, DVD+RW, and the like are available.
As for the write-once information recording media, on which data can be written only once, CD-R, DVD+R, and the like are available.
The write-once type information recording medium, such as a CD-R and a DVD+R, stores data by making a hole in a recording film on the disk with a high power laser light.
On the other hand, the rewritable type information recording medium, such as a CD-RW disk and a DVD+RW disk, stores data by a phase change method, wherein a reflectance difference between a crystalline state and an amorphous state is employed.
Physical properties, such as reflectance, of the write-once medium are different from physical properties of the rewritable medium. For this reason, a recording strategy for the write-once medium is different from a recording strategy for the rewritable medium. Here, the recording strategy refers to an output pattern of the laser light irradiated when recording data. Even when the same data are to be recorded, the output strength and irradiation period of the laser light for the write-once medium differ from those for the rewritable medium. There are cases where the rewritable medium, the reflectance of which is lower than the write-once media, cannot be reproduced by an information reproducing apparatus, such as a common CD player and a DVD player.
While reproducing data from a CD-RW disk is becoming possible for a large number of information reproducing apparatuses, reproducing data from a DVD+RW disk remains a problem, only about two thirds of the information reproducing apparatuses being able to so reproduce.
This is because the rewriting standards of DVD disks, such as DVD+RWs, have not been diffused widely, and there is a compatibility problem.
The write-once information recording media, such as CD-Rs and DVD+Rs, have a high reflectance, and reproduction is possible by nearly 100% of the common CD players and common DVD players.
Further, the data recording format for the CD-R disks and the CD-RW disks is prescribed by a standard called the Orange Book, and is compatible with stamped CD disks for reproduction. That is, the CD-Rs and the CD-RWs can be reproduced by common CD players, and the like.
There are several kinds of data recording formats for the information recording media. A format that provides the highest compatibility with the CD player is a recording format called disk-at-once, often referred to as “DAO”.
According to the DAO format, all zones, including a lead-in zone, a program zone (program area), and a lead-out zone, are recorded in this sequence in one operation. A disk recorded according to the DAO format has the same structure as a stamped CD, and thus provides the highest compatibility with the commom CD player.
Other recording formats include track-at-once “TAO”, where incremental recording is possible in the unit of tracks, there being a maximum of 99 tracks; session-at-once SAO, where recording is carried out session by session; and packet-write, where recording is carried out packet by packet.
The data recording format for the CD-R disk is fundamentally the same as that for the CD-RW disk. Therefore, it is often practiced that tentative recording is carried out on a CD-RW, and if successful, recording on a CD-R is carried out. In this manner, if an unsatisfactory result is obtained in the tentative recording, the CD-RW can be reused, before final recording on the CD-R is carried out.
In other words, a CD-RW disk is often used for proving (testing) purposes, and CD-R disks are often used for distribution.
As described above, in the case of CD, the data recording format for the write-once CD-R is the same as the rewritable CD-RW, and the above usage is possible.
On the other hand, in the case of DVD, the data recording format for a DVD+R disk is different from that for a DVD+RW disk. Unlike the CD, the DVD+R disk does not make a distinction between TAO and DAO. In the case of the DVD+R, data are recorded sequentially. In order that the DVD+R sequential data recording format may provide compatibility with a DVD-ROM disk drive, a portion is reserved for recording file information, and when closing a session, the file information is recorded in the reserved portion. Further, although the sequential recording on a DVD+R has to sequentially store data from the innermost circumference of the disk and outward, the sequence of data to be recorded can be interchanged by reserving two or more portions for recording. Further, recording is possible by a so-called multitrack-multisession method, wherein incremental recording is possible in the units of tracks and sessions.
In contrast, basic data recording formats for a DVD+RW disk are by tracks and by sessions. Unlike the DVD+R, the DVD+RW needs a formatting process wherein specific data are provided all over the disk, before the disk can be used for recording user data. The DVD+RW formatting process is a time consuming step, and user-unfriendly. Recently, a method has appeared, wherein only a certain minimum area is formatted initially, and the remainder is formatted in the background, such that data recording and reproduction are available quicker.
In this manner, a user can use the DVD+RW disk sooner than before, minimizing the time spent for formatting. Here, the disk can be ejected during the background formatting.
Here, a consideration is given to the fact that a DVD-ROM reproducing apparatus requires that a disk to be reproduced be filled with data to a certain extent. In view of this requirement, there is a method wherein a DVD+RW can be ejected only after dummy data are filled to the certain extent, in addition to a method wherein the disk can be ejected immediately.
As mentioned above, since the data recording format for the write-once DVD+R is different from the rewritable DVD+RW, a problem is that the task sharing between the CD-RW disk and CD-R disk for experimental use and distribution use respectively, often practiced as described above, is not available with the DVD+R and DVD+RW, due to the difference in the recording format. For this reason, in the case that a large amount of information recording media are consumed, like the research and development in connection with an information recording medium, the problem of the large consumption of the information recording media arises, without the task-sharing ability of performing experiments with a rewritable DVD+RW then distributing DVD+Rs with the same contents.